1. Field of the Invention
The present invention relates to telephone-line connection performed for a call-connection device (a switching device and/or a session-initiation-protocol (SIP) server) configured to connect a call from an originating terminal to a destination terminal, and particularly relates to call connection performed for the call-connection device, the call connection being performed, for example, when a disaster or the like occurs.
2. Description of the Related Art
When a disaster occurs, the switching device and/or the SIP server becomes crowded with safety-confirmation calls made for people staying in the disaster area. In that case, line congestion and/or network congestion occurs due to increased traffic, which makes it difficult to confirm the safety of the people staying in the disaster area in a timely manner.
The prior art describes a safety-confirmation-message-board service being employed when a disaster occurs. However, even if a safety-confirmation-message-board service or the like is provided, the service is not practical enough to confirm the safety of the people staying in the disaster area in a timely manner. Further, advance knowledge, such as using a special phone number, is required so as to use the above-described service.
Still further, the above-described service requires the installation of message-accumulation servers at many sites in the country in a distributed manner. The above-described technologies have been disclosed in Japanese laid open patent application No. 8-317471 and Japanese laid open Patent application No. 2003-348638, for example.